Raymarine...Reasonable price. I am sorry but gramatically those two words do not go well together. The bit of kit you are asking about will set you back the thick end of 200 sovs.
I have the same problem, but I think it is just the vane and cups which have blown away. I see from the jgtech link (thankyou)
that you can get a service kit with these for £29, so I am hoping that is all. I hope it is the same for you.